520 K ILOWATT SOLAR P HOTOVOLTAIC A RRAY SEWERAGE COMMISSION— O ROVILLE REGION, C ALIFORNIA

Abstract

During 2001, the state of California experienced frequent power
outages coupled with rapidly rising electric rates. Even prior to 2001,
the Sewerage Commission—Oroville Region located in northern Cali-
fornia saw its energy costs skyrocket by 41%. In this uncertain energy
environment, the superintendent of the sewerage commission investi-
gated alternative energy sources that would stabilize its energy supply
and reduce energy expenses. Normally, cost increases would be
passed on to the rate payers in the form of higher utility bills. The
result was the installation of a 520-kW solar photovoltaic (PV) array,
consisting of 5,184 panels on three acres of unused land adjacent to
the treatment ponds. The solar system combined with the utility credit
reduced annual net power bills by over 80%. The PV system was
commissioned and went on line in November 2002. The solar array is
the largest dual-tilt array in the world and one of the largest PV ar-
rays in the United States. It is also the only wastewater treatment
plant in the U.S. to be primarily powered by solar energy.